With the development and advancement of wireless communication technologies, related applications also increase extensively. Among these wireless communication technologies, those applied to apparatus moving in high speed have attracted much attention. For example, vehicles on-road can retrieve information (e.g., electronic maps, road condition information, parking information and so on) necessary for driving by wireless communication technologies. As examples of other applications, the wireless communication technologies may also be used for communication between vehicles or allow passengers to retrieve network information in real time.
In general network environments, the conventional way in data transmission is through a Transmission Control Protocol/User Datagram Protocol (TCP/UDP) module. In the Open System Interconnection (OSI) Reference Model, TCP/UDP belongs to a communication protocol of the fourth layer (i.e., the transmission layer), and the third layer (i.e., the network layer) adopts the Internet Protocol (IP). Therefore, according to the specifications of the Internet Protocol, two points which are desired to connect directly with each other for communication must be restricted within a same subnet.
If a TCP/UDP transmission module is used for a moving vehicle in a Wireless Access in Vehicular Environment (WAVE)/Dedicated Short Range Communication (DSRC) operating environment, firstly the moving vehicle must know the subnet in which it is located before performing data transmissions. However, as the moving vehicle continuously changes its position, the subnet in which it located also changes continuously, and this may lead to communication interruptions and poor communication quality.
Therefore, in the WAVE/DSRC environment, a commonly used way of communication is through use of the Wave Short Message Protocol (WSMP). The WSMP is characterized in that, data transmissions are carried out in a broadcast manner and are identified through provider service identifiers (PSIDs), and the two points which are desired to connect directly with each other for communication need not to be restricted within the same subnet. Therefore, data transmissions in the WAVE/DSRC environment have greater flexibility and can provide desirable transmission quality. However, WSMP still has a drawback that it cannot provide reliable transmission.
Accordingly, there is a need to provide a message conversion apparatus and a message transmission method capable of converting packets between communication protocols, supporting reliable transmissions and carrying out data transmissions with a TCP/UDP module so that the user needs not to change the design framework of application programs.